I am currently in the process of building a 12v portable softwash system on a cart. It will be using a 5gpm pump at 70 psi. I plan on using Apple Wash as the surfactant, I also have EBC (unsure if anyone uses that in a roof mix).
I have been approached to clean a concrete tiled roof as he wants it clean for painting. From my research on here and on YT, the consensus is that if there is heavy organic growth present on the roof, you simply leave it to fall off with the wind and the rain after treating it with your roof mix.
My question is that if there is heavy organic growth (picture below is from the rental I currently live in, lots of lichen present) on this concrete tiled job, he will expect it all gone once I have left as presumably he won’t want to wait 6-12 months for the lichen to fall off in its own time before painting it. What suggestions do you have to turn a roof like the one pictured into one that is clean and free of heavy lichen?
Personally I think its unrealistic given the type of growth present and the amount to expect all traces of it to be gone from the roof once I’m finished.
I think the only way is to either 1) use low pressure to try and rinse it off or 2) use a broom to brush it off. As its a concrete tiled roof, I don’t think it would be a great idea to be walking on it as tiles could be damaged.
I would love to hear any suggestions or tips on removing heavy lichen growth.